Warriors back-row Leonardo Senatore scored a try as Argentina fought back from 14-0 down to beat Australia 21-17 in Mendoza on Saturday.
The Pumas ended three years of frustration and near-misses at the 18th attempt, and sparked scenes of wild celebration in the stands in Mendoza.
Both sides scored two tries apiece, the difference being the trusty boot of Pumas fly-half Nicolas Sanchez – and controversially, a laser pen trained on the eye of Wallabies fly-half Bernard Foley as he took a vital penalty in the second-half.
Argentina were stunned by a brilliant start from the visitors who marched into a 14-0 lead after 13 minutes through tries for centre Tevita Kuridrani and number-eight Scott Higginbotham.
The Pumas hit back in superb style after 13 phases of attack, with number-eight Senatore crossing in the right corner for a rousing team try.
Sanchez failed with the conversion but slotted his first points from a penalty on the stroke of half-time to cut Australia's lead to 14-8.
The tiring Australians lost their discipline in the second half, with two men sin-binned by referee Nigel Owens.
Scrum-half Nick Phipps was the first, shortly after the break, and Sanchez slotted his second penalty to make it 14-11.
The Aussies thought Kuridrani had scored in the corner, only for the TMO to rule it out after a lengthy video review, but Foley did convert a penalty to restore his side’s six-point lead.
But then the hosts took over with winger Juan Imhoff crossing for the Pumas' second try and Sanchez's conversion put the hosts ahead for the first time in the 53rd minute.
With ten minutes left, Foley had a chance to put his team back in front with a penalty kick from close range but hit the post after having a laser pointed at his face from the crowd.
On 74 minutes, a yellow card saw Wallabies captain Michael Hooper sin-binned for a dangerous challenge on Sanchez and the fly-half nailed the penalty.
The Aussies could find no way back and the Pumas held on for a momentous victory.
The win, in the final round of the tournament, was Argentina's first over Australia since 1997, and ended a run of eight straight international defeats, including the summer tours.
The closest the Pumas had come to victory in the Championship was in their maiden tournament in 2012, a 16-16 draw with South Africa at the same Malvinas Argentinas stadium.
Duo Creevy and Senatore will return to Sixways later this month.